The urinary system helps to maintain proper water and salt balance throughout the body. The process of urination begins in the two kidneys, which process fluids and dissolved waste matter to produce urine. Urine flows out of the kidneys into the bladder through two long tubes called ureters. The bladder is a sac that acts as a reservoir for urine. It is covered with a membrane and enclosed in a powerful muscle called the detrusor. The bladder rests on top of the pelvic floor. This is a muscular structure similar to a sling running between the pubic bone in front to the base of the spine. The bladder stores the urine until it is eliminated from the body via a tube called the urethra, which is the lowest part of the urinary tract. (In men it is mostly enclosed in the penis. In women it leads directly out. In either case the urine outlet opening is called the urinary meatus.) The connection between the bladder and the urethra is called the bladder neck (which includes the bladder outlet opening). Strong muscles called sphincter muscles encircle the bladder neck (the smooth internal sphincter muscles) and urethra (the fibrous external sphincter muscles).
The process of urination is a combination of automatic and conscious muscle actions. There are two phases: the emptying phase and the filling and storage phase. When a person has completed urination, the bladder is empty. This triggers the filling and storage phase, which includes both automatic and conscious actions.
An automatic signaling process in the brain uses a pathway of nerve cells and chemical messengers (neurotransmitters) called the cholinergic and adrenergic systems. The brain signals the detrusor muscle, which surrounds the bladder, to relax. As the muscles relax, the bladder expands and allows urine to flow into it from the kidneys. As the bladder fills to its capacity (about 8 to 16 oz of fluid) the nerves in the bladder send back signals of fullness to the spinal cord and the brain.
As the bladder swells, the person becomes conscious of a sensation of fullness. In response, the individual holds the urine back by voluntarily contracting the external sphincter muscles (the muscle group surrounding the urethra). (These are the muscles that children learn to control during the toilet training process.) When the need to urinate overcomes the conscious holding back, then urination (the emptying phase) begins. At the point when a person is ready to urinate, the nervous system initiates the voiding reflex. In this case, the nerves in the spinal cord (not the brain) trigger the event. These nerves signal the detrusor muscles around the bladder to contract. At the same time, nerves are also signaling the involuntary internal sphincter (a strong muscle encircling the bladder neck) to relax. With the bladder muscles squeezing and its neck open, the urine flows out of the bladder into the urethra. Once the urine enters the urethra a person consciously relaxes the external sphincter muscles, which allows urine to pass out. Urine is then completely drained from the bladder and the process of filling and storing begins again.
Urinary Incontinence
In a person with urinary incontinence (UI) the muscles, nerves, or both are no longer under that person's control. This presents the problem of controlling the release and containment of urine. UI affects all aspects of a person's life and may affect their health. Urinary incontinence is an underreported problem estimated to afflict about 25-50 million people in the United States. The annual direct costs (does not include indirect or hidden costs) of providing care for persons with UI is estimated to be in excess of $16 billion (year 1995). Urinary incontinence is one of the most common chronic medical conditions seen in primary care practice. UI is more prevalent than diabetes, Alzheimer's disease, and many other conditions that receive considerably more attention.
Incontinence is an expensive problem, generating more costs each year than coronary artery bypass surgery and renal dialysis combined. Women have higher rates of urinary incontinence than men. Prevalence increases with age, one third of women older than 65 years have some degree of incontinence, and 12 percent have daily incontinence. A shift to a healthier, more active and older population and a society which is increasingly mobile is resulting in an increasing number of persons suffering from incontinence, and a demand from that population for more effective and reliable solutions for urinary incontinence.
Pharmaceutical companies have developed several new incontinence medications. Sales of these medications were predicted to measure billions of dollars in 2004. The market for adult absorbent devices or diapers alone is in excess of $2 billion and continues to grow. Total sales of products used in the diagnosis and treatment of UI were estimated at $1.37 billion in 2001. Due to the size of both current and potential UI markets, medical professionals and product manufacturers have placed significant emphasis on research into the diagnosis and treatment of this condition, which has resulted in the development of several new therapies and approaches that could potentially delay UI symptoms for years in some patients.
UI can affect persons of all ages, and may be the result of physical disability or a psychological condition. There are several different types of incontinence. Acute (or Transient) Incontinence is caused by generally treatable medical problems. Medical conditions such as dehydration, delirium, urinary retention, fecal impaction/constipation, and urinary tract infection; can cause an onset of UI. Additionally, certain medications can cause or contribute to an incontinence problem, such as anticholinergic agents, antihistamines, antidepressants (TCA), phenothiazines, disopyramides, opiates, antispasmodics, Parkinson drugs, alpha-adrenergic agents (high blood pressure drugs), sympathomimetics (decongestants), and sympatholytics (e.g., prazosin, terazosin, and doxazosin).
Chronic UI is conventionally classified into four groups: Stress, Urge, Overflow, and Functional incontinence. They may occur alone or in combination, the latter being more common as the patient ages. Chronic UI is persistent and more difficult problem to treat. Often, more than one type of incontinence is present. Approximately 40% of all incontinence cases fall into more than one of the four categories. A variety of disease and medical problems may contribute to each of the four major types of incontinence. Because incontinence is a symptom rather than a distinct disease, it is often difficult to determine a definite cause.
Stress incontinence is the involuntary leakage of small amounts of urine resulting from an increased pressure in the abdomen. Events which may result in such involuntary leakage include sneezing, coughing, laughing, bending, lifting, etc. While primarily a female problem, men also suffer from stress incontinence. Stress incontinence in men is typically the result of a weakened urethral sphincter that surrounds the urethra, frequently as a result of prostate surgery.
Urge incontinence, characterized by insufficient ability to prevent voiding once the urge to void arises, is most common in middle aged and older people. Detrunorm hyperreflexia or instability which is associated with disorders of the lower urinary tract or neurologic system is a common cause. However, urge incontinence can also be the result of urologic carcinoma, diverticula, or other physical abnormalities.
Overflow incontinence, which accounts for 10-15% of urinary incontinence, is usually the result of an obstruction (e.g., enlarged prostate, urethral stricture) of the bladder outlet or an atonic bladder as the result of neurologic injury (e.g., spinal cord trauma, stroke), diabetic neuropathic bladder, or drug-induced atonia. The obstruction leads to bladder overfilling, resulting in a compulsive detrusor contraction. In this form of UI chronic “dribbling” is common. Drug induced atonia can be caused by anticholinergics, narcotics, anti-depressants, and smooth muscle relaxants.
Functional incontinence accounts for 25% of all incontinence. It occurs primarily when a person is confined and sedentary, such as in a nursing home or during a long period of convalescence. Functional incontinence is sometimes diagnosed as a result of the individual simply being unable to communicate his or her needs, or through other sensory impairments that make the individual unaware of his or her need to void. This condition can further result from decreased mental function, decreased functional status, and/or a simple unwillingness to physically go to the toilet.
UI, or even the fear of an incontinent incidence, can lead to discomfort and embarrassment, and eventually to social withdrawal and isolation. Normal activities, social interaction, and sexual activity are often curtailed or avoided as a result. According to the National Association For Continence, (NAFC), incontinence is the predominant reason aging parents patients are put admitted into nursing homes. Urinary incontinence is a chronic (long-term) problem.
Treatment of Urinary Incontinence
The current protocols for treating urinary incontinence from least to most invasive are education and behavior therapy, pelvic floor muscle exercises, absorbent pads, external devices, medication, non-surgical implants, surgery procedures, and surgical implants.
Pelvic muscle training exercises called Kegel exercises are primarily used to treat people with stress incontinence. However, these exercises may also be beneficial in relieving the symptoms of urge incontinence. The principle behind Kegel exercises is to strengthen the muscles of the pelvic floor, thereby improving the urethral sphincter function. The success of Kegel exercises depends on proper technique and adherence to a regular exercise program. Minimally invasive therapies can lead to improvement in incontinence but not necessarily a cure. Improvement generally does not occur overnight. Patients need time to adapt to behavioral changes. Results with pelvic floor exercises may typically take three to six months.
Diapers and other absorbent constructions are the most popular remedy because they are easily obtained, and can address acute UI symptoms quickly. However, while affording reasonably effective control of urine leakage and providing mobility to the patient, absorbents also have very serious drawbacks. A major deficiency is that urine is not removed from the genital region. The absorbents merely collect and disperse the urine and maintain a moist environment with the urine typically remaining in contact with skin surfaces, causing irritation and discomfort. While improved constructions with different absorbent layers attempt to direct the urine to a region away from the skin and minimize contact, the resulting benefit is less then desired. Absorbent devices also require a large area of absorbent material surrounded by water proof external barriers, usually in the form of pants or diapers. Such an arrangement when dry is uncomfortable to the wearer. When wet the discomfort level increases greatly and the wearer must deal with the distinctive, embarrassing odor of urine. Once removed, whether soiled or not, the disposable-type diaper usually must be disposed of, creating the need to always carry a supply of such absorbent devices.
Catheters
Incontinence treated by catheterization, use of absorbent products, and for males, devices attached to the exterior surface of the penis to collect urine discharge have many disadvantages. Catheterization, whether intermittent or permanent, is an unacceptable approach in many instances and is the least preferred type of incontinence management. The procedure is very inconvenient and many patients are psychologically averse to self-catheterization, or physically unable to perform the manipulations required. Catheters need to be changed frequently. A major deficiency of either permanent or intermittent catheterization is that the urine of virtually every patient becomes contaminated by bacteria. Catheter-associated bacteria or catheter associated urinary tract infection (CAUTI) represent the most common infection acquired in acute care and long-term care facilities. Complications ranging from bladder spasms and catheter leakage to death caused by septicemia are also well known limitations. Bacterial entry into the bladder occurs either from extra luminal migration along the outside of the catheter, contamination on insertion of the catheter, or contamination of the drainage bag, leading to bacterial growth and subsequent migration into the bladder.
The catheter is inserted in and out of the urethra causing a physical manipulation of urethral tissue that may result in scarring, erosion and/or expansion of the urethra, and is generally painful due to nerve endings within it.
Indwelling Catheters are only permitted for insertion up to 30 continuous days, then must be replaced. Indwelling catheters hang from a patient's genitals, thereby interfering with intimacy and sex.
Finally, all types of catheters (indwelling, intermittent, and condom) enable urinary incontinence.
Medications
Pharmaceutical companies have developed several new incontinence medications. Sales of these medications were predicted to measure billions of dollars in 2004. These drugs are useful in treating urge incontinence, but they can have distressing side effects that limit their use, and compliance is poor. Some patients may notice an immediate effect with medical therapy, whereas in others an effect may not be seen for approximately four weeks. Incontinence may also recur after treatment. The disadvantage of medication such as oxybutynin, (including trade names: DETROL® by Pharmacia & Upjohn (now Pfizer), and DITROPAN® by J&J), is the unwanted side effects. Side effects such as dry mouth, nose, and throat, dizziness, drowsiness, and confusion, decreased sweating and skin rash, nausea and constipation, eye pain, and rapid heartbeat.
Surgical Implants
Surgical implant treatments include mid-urethral slings, injection of bulking agents (collagen, etc.) under the bladder neck to provide support, balloons under the bladder neck to provide support, and female urethral inserts. There are nearly 200 procedures for incontinence. Most of these procedures are designed to restore the bladder neck and urethra to their anatomically correct positions in patients with stress incontinence. The American Urological Association suggests that surgery should actually be considered as initial therapy for women with severe stress incontinence. It is an effective and safe alternative when conservative treatments fail. Potential complications of all procedures include obstruction of the outlet from the bladder, causing difficulty in urination and irritation. Another problem with these implants include the fact that bulking agents such as collagen lose their effect and need to be continually reapplied. Some surgical methods such as slings only work in females but are currently a subject of product litigation related to long term effects.
Recent advanced technology implants include electrical nerve stimulation (“e-stim”), and a urethral cuff.
E-stim generally comprises wires carrying electrical pulses from a pacemaker-like stimulator to the bladder sphincter muscles. The wires must be surgically implanted and the stimulator module may be implanted or kept outside the body, in which case medical care is required to prevent infection or damage to the wires where they enter the body. E-stim has limited utility: it only works for urge incontinence, and then provides only about 50% reduction in incontinence. Furthermore, the stimulator may have to be repeatedly reprogrammed as the body becomes less sensitive as it is accustomed to a given level of electrical stimulation. Also, may need to disconnect or remove the device with the onset of Alzheimer's.
The cuff is a hollow tubular sleeve that is surgically positioned around the urethra. An inflatable cushion is inside of the cuff, and a balloon reservoir and pump are interconnected by tubing. The reservoir is implanted in the abdominal cavity, and the pump is placed in a man's scrotum, or subdermally in a woman's lower abdomen. Besides problems positioning the pump in a woman's body where it can be manipulated, it is often prohibitive to implant the cuff due to the very short length of her urethra (e.g., only 1.5-2″).
When the pump is hand manipulated the cushion inflates, which compresses the entire perimeter of the natural urethral tissue radially inward. Although intended to work like a sphincter valve, a problem is that it acts on the outside diameter of the urethra (urine conduit), unlike a natural sphincter which is included in the tissue of the urine conduit, so that it closes by making elastic changes in the conduit walls, i.e., deforming itself to reduce its inside diameter to essentially zero. On the other hand, the cuffs radial compression applied to the outside diameter of the urethra/conduit must change the conduit wall to a smaller circumference (a smaller annular volume), which means that some of the tissue mass must be moved out of the way, e.g., by radial compaction into a smaller volume and/or by longitudinal extrusion and/or by wrinkling the ID. The urethra itself is not designed to do any of those things, therefor it is traumatized whenever it is compressed by the cuff, which is most of the time except when voiding. Furthermore, the urethra is living tissue which needs blood circulation that may be restricted by the outside compression. And if the cuff ID wrinkles when compressed, then that creates a wrinkled ID surface which is may abrade and/or pinch the urethra surface. Finally, the longer the cuff compression zone is, the worse the trauma to the urethra tissue may be (because annular volume is proportional to length).
Other problems common with the cuff include: bladder neck and scrotum erosion and ischemic injury; disconnection or migration of the components; pressurizing fluid leakage or breakage of the components; may need to disconnect/disable or remove the device with the onset of Alzheimer's. Also, implantation of the cuff requires several invasive surgeries over the course of about 12 weeks: implant components, let swelling go down, hook up components via surgery, let swelling go down, then activate the device.
Bladder Replacement and Urinary Diversion Surgeries
The abovedescribed implants are designed to improve function of an existing bladder, however incontinence must also be dealt with when the bladder (with sphincters) is surgically removed (aka cystectomy), such as may be necessary due to, for example, bladder cancer, injury/abdominal wounds, and other types of bladder destruction. In such cases, urinary diversion and/or surgical bladder replacement/reconstruction are the remaining options presently available. Other current surgical methods offer only temporary solutions.
A urostomy is a surgical procedure that creates a stoma (artificial opening) for draining the urinary system by diversion of the urine flow. A urostomy may be used for temporary urinary diversion in cases where drainage of urine through the bladder and/or urethra is not possible, e.g. after extensive surgery or in case of obstruction; however a urostomy is most commonly performed after cystectomy (bladder removal).
The three main types of urinary diversion surgeries suitable for use after cystectomy are ileal conduit, Indiana pouch reservoir and orthotopic neobladder.
With the ileal conduit, the ureters drain freely into part of the ileum (the last segment of the small intestines) and urine is brought out through an opening, called a stoma, in the abdominal wall and an external bag gathers urine as it drains from the ileal conduit.
The Indiana pouch is made out of portions of the large intestine, so no urine collection bags are needed, but a catheter must be passed through the stoma and into the pouch to empty urine.
The neobladder (a.k.a. “continent urostomy”) is a tissue construct replacement bladder formed out of a transplanted segment of small bowel (intestines). The small bowel tissue is surgically formed into a bladder-like reservoir (or “pouch”) which is connected between the ureters and the urethra, and then urine is evacuated via a catheter inserted into the urethra to empty it (since the bladder sphincter is gone). This technique avoids the need for a stoma bag on a urostomy, but instead presents the infection and other problems caused by catheter use.
These urinary diversion procedures have disadvantages and adverse effects such as osteoporosis and bowel tissue absorbance of urine and catheters inserted into stoma to void urine can introduce bacteria into the body leading to infections. Current orthotopic neobladder procedures that make use of intestinal cells cause the body to absorb osteoporosis-causing calcium and other substances that a normal bladder eliminates from the body. Despite its adverse effects and limitations, the use of bowel segments remains the gold standard as of today.
A prior art implantable bladder replacement device by Griffith, U.S. Pat. No. 4,976,735 (issued 1990) includes a prosthetic bladder that doesn't collapse when drained, therefor it requires an air vent through the body of the patient. The vent creates problems related to contamination and leakage.
In an effort to find an alternative to use of bowel segments in his pediatric surgical practice—as there was a shortage of organs (in this case bladders) and not enough donors to meet the high demand—Dr. Anthony Atala began research in 1990 on how to successfully create and implant a functioning artificial bladder grown from autologous human cells (urothelial and smooth muscle cells from the receiving patient) via a tissue engineering approach. Problems with Atala's and others' tissue engineered artificial bladders or constructs are that: autologous cells must be cancer free; there is a lack of sufficient nerve conductivity and blood flow; and the inability to create a functional valve construct to make the artificial bladder fully functional on its own. Thus with an artificial bladder or construct patients must still empty their bladders regularly with a catheter. A functional valve construct could make this a viable solution.
Clinicians who work daily with patients with severe bladder dysfunction, UI and retention issues, know and appreciate the importance of having technologies to assist in improving their patients' overall health by mitigating existing conditions; thus resetting the patients for their return to work, duty, and daily life. Currently there is a subset of patients for whom clinicians have limited or even no options other than a urethral catheter and being placed in an institution to be cared for as family becomes overwhelmed with their care issues.
Urinary incontinence affects the quality of life for all those who are afflicted with it, or who care for them. The current methods of treatment do not provide adequate remedies or treatments for urinary incontinence, and all introduce extra problems ranging from life limiting inconvenience to infections that can even be life threatening. Therefor it is an object of the present invention to provide a device and method that remedies urinary incontinence while overcoming the problems and limitations of current methods such as those described above, thereby significantly improving quality of life for the users.